Version 1.0, 15 May 2011

Stage 1, Module 5

Copyright © 2011 Ted Dudley

Objectives

For the student to understand the factors which affect the physiology of flight

To become familiar with the regulations which govern the student and private pilot, and general aviation flight

Fitness to Fly

HEY!You can get pretty seriously killed doing this

stuff!Particularly if you’re not both physically and

mentally prepared to fly every time you step towards the airplane

You must always answer the question “Am I fit to fly today?”

Not just in training: every time for the rest of your life

Physical Fitness to Fly

After your medical is issued, the only person that checks your fitness to fly is you. Take into account: Illnesses/injuries Medications Cold/upper respiratory infection Use of corrective lenses Food poisoning Alcohol/tobacco use Fatigue Blood donation

Mental Fitness to Fly

Nobody ever checks for this except youIf you don’t feel like flying today, don’t fly!

Not mentally prepared for a training ride Emotionally in turmoil

Grief Anger Fear Problems with loved ones Problems at work

Medical Checks

Annual checkup, though not required for Class III, is a good idea Your doc may find things that can be dealt with before

the FAA gets involved Many things are easily treated if found early

Medication

Many common meds are not approved for use when enjoying the privileges of your certificate For example, most over the counter cold medications

It’s your responsibility to know what they areYou probably don’t know, so ask your Aviation

Medical ExaminerThey’re not approved because they could

affect your ability to fly safely

Upper Respiratory Problems

Tissue swelling associated with a cold or upper respiratory infection can block: Eustachian tubes Sinuses

Eustachian Tube Blockage

Eustachian tubes equalize air pressure on either side of eardrum and you experience much pressure changing in flight

Yawning naturally opens Eustachian tubesNormally, you can force pressure equalization with a

valsalva maneuver: Pinch the nostrils shut Close the mouth and lips Blow slowly and gently in the mouth and nose

Blocked Eustachian tubes reduce hearing sensitivity, can cause ear pain

Badly blocked Eustachian tubes could result in ruptured eardrums

Sinuses are cavities in the skull that contain airNormally connected to nasal passages for

equalization of air pressureBlocked sinuses can be excruciatingly painful, as

air trapped in the sinus expands and increases pressure on tissues

Occurs most frequently during descentSlow descent rates can reduce the associated

painBadly blocked sinus can lead to structural

damage of the sinus

Sinus Block

Corrective Lenses

Your Medical Certificate may require you to fly with corrective lenses

Even if not, if glasses/contacts help you, wear them

You can’t see and avoid if you can’t seeAlways a good idea to have a spare or backup

with you

Food Poisoning

Can easily debilitate you from 30 minutes to six hours after eating

Probably don’t want to try the raw oysters just before flying

Alcohol

Don’t be a knucklehead! Alcohol always interferes with your ability to operate an aircraft

14 CFR 91.17 says no person may operate or attempt to operate an aircraft: within 8 hours of having consumed alcohol while under the influence of alcohol with a blood alcohol content of 0.04% or greater while using any drug that adversely affects safety

It’s not hard to have a blood alcohol content higher than 0.04% even after 8 hours since consumption

Best if there is no alcohol left in you when you fly

Smoking

Tobacco smoke causes mild carbon monoxide (CO) poisoning

Smoking at sea level can raise the CO concentration in the blood and result in physiological effects similar to flying at 8,000 feet

Besides hypoxia, tobacco causes diseases and physiological debilitation that are medically disqualifying for pilots

Fatigue/Sleep Deprivation

Fatigue causes Degradation of attention and concentration Impaired coordination Decreased ability to communicate

…none of which are helpful to your ability to make effective decisions

Acute fatigue can be prevented by proper diet and adequate rest and sleep

If fatigue occurs in the flight deck, no amount of training or experience can overcome the detrimental effects

If suffering from acute fatigue, stay on the ground

Blood Donation

Giving blood causes a type of hypoxiaFAA policy: An airman who has donated

200cc or more for plasmapheresis or blood donation should not fly for at least 24 hours

Low Temperatures

We’re flying a single engine airplane – someday, that engine won’t work any more

If that happens while we’re in it, we’ll land somewhere, maybe far from any airport or road

Plan to spend a night in that caseAlways dress for survival in that eventuality

Think how disappointed you’ll be when you survive the landing, then freeze to death

Respiration and Flying

Increased altitudeHypoxiaCarbon monoxide poisoningHyperventilationDecompression sickness

Increased Altitude

Atmospheric pressure decreases with altitudeAs the airplane ascends during flight, the

percentage of each gas in the atmosphere remains the same, but there are fewer molecules available

At very high altitudes, low pressure can cause decompression problems

Hypoxia

Means “not enough oxygen”You need a certain amount of oxygen to

function normallyThere are several kinds of hypoxia, but the

one you’re most likely to encounter in small airplanes is hypoxic hypoxia As the airplane ascends during flight there are fewer

molecules available at the pressure required for them to pass between the membranes in the respiratory system

This results in not enough oxygen for you to function normally

Hypoxia Symptoms

Symptoms vary with individuals, but may include Cyanosis (blue fingernails and lips) Headache Decreased reaction time Impaired judgment Euphoria Visual impairment Lightheaded or dizzy sensation Tingling in fingers and toes Numbness

Hypoxia Cure

Descend!Use oxygen if available

Carbon Monoxide Poisoning

Exhaust gases contain large amounts of carbon monoxide (CO), which is odorless and colorless

Carbon monoxide is deadly and quick actingThere is a CO detector in the cabinIf the spot turns dark…

Cabin heat – closed Ventilate the cockpit as much as

possible

Hyperventilation

Excessive rate and depth of respiration leading to abnormal loss of carbon dioxide (CO2) from the blood If you breathe very rapidly (usually as a response to

emotional stress), you expel more CO2 through your lungs than usual

Your nervous system interprets low blood CO2 as a signal to automatically breathe faster

Breathing can still be consciously controlled

Hyperventilation Symptoms

Abnormally rapid breathingOther symptoms similar to hypoxia:

Visual impairment Lightheaded or dizzy sensation Tingling sensations Hot and cold sensations Muscle spasms Unconsciousness

Hyperventilation Cure

Consciously slow breathing to a normal rate Breathing normally will raise blood CO2 level

Breathe into a paper bag Rebreathing air from the bag will raise blood CO2

levelTalking out loud

You can’t breathe fast and talk at the same time

Decompression Sickness (DCS)

At very high altitudes (and low pressure), gases dissolved in body tissues and fluids come out of solution and form bubbles Much like taking the cap off a soda bottle

These bubbles can cause moderate to severe neurological damage and death

Generally not a problem at the altitudes we’ll fly in trainingFlying after scuba diving makes DCS more likely

Waiting time before going to flight altitudes of up to 8,000 feet: At least 12 hours after diving that does not require controlled ascent

(nondecompression stop diving) At least 24 hours after diving that does require controlled ascent

(decompression stop diving) Waiting time before going to flight altitudes above 8,000 feet should be at

least 24 hours after any scuba dive

Orientation and Balance

The body uses three integrated systems working together to ascertain orientation and movement in space Visual system—eyes, which sense position based on

what is seen Somatosensory system—nerves in the skin, muscles,

and joints, which, along with hearing, sense position based on gravity, feeling, and sound

Vestibular system—organs found in the inner ear that sense position by the way we are balanced

Visual System

During flight in visual meteorological conditions (VMC), the eyes are the major orientation source

The visual system almost always prevails over false sensations from other sensory systems

When visual cues are removed, as they are in instrument meteorological conditions (IMC), false sensations can cause a pilot to quickly become disoriented

Sensing Acceleration

The somatosensory system sends signals from the skin, joints, and muscles to the brain that are interpreted in relation to the Earth’s gravitational pull It tells you “which way is up”

“Seat of the pants” flying is largely dependent upon these signals

In conjunction with visual and vestibular clues, these sensations can be fairly reliable

However, the body cannot distinguish between acceleration forces due to gravity and those resulting from maneuvering the aircraft

This can lead to sensory illusions and false impressions of an aircraft’s orientation and movement

Inner Ear Balance Mechanism

The vestibular system in the inner ear allows the pilot to sense movement and determine orientation in the surrounding environment

In both inner ears, three semicircular canals are positioned at approximate right angles to each other

Each canal is filled with fluid and has a section full of fine hairs

Acceleration of the inner ear in any direction causes the tiny hairs to deflect, which in turn stimulates nerve impulses, sending messages to the brain to interpret motion

Vestibular System

Vestibular System

Under normal flight conditions, when there is a visual reference to the horizon and ground, the sensory system in the inner ear helps to identify the pitch, roll, and yaw movements of the aircraft

When visual contact with the horizon is lost, the vestibular system becomes unreliable

Without visual references outside the aircraft, there are many situations in which combinations of normal motions and forces create convincing illusions that are difficult to overcome

Sensing Angular Acceleration

Motion Sickness

Motion sickness, or airsickness, is caused by the brain receiving conflicting messages about the state of the body

You may experience motion sickness during initial flights, but it generally goes away within the first few lessons

Lots of excellent pilots have experienced motion sickness during initial training

Motion Sickness

If symptoms of motion sickness are experienced during a lesson: Open fresh air vents Focus on objects outside the airplane Avoid unnecessary head movements

Although medications like Dramamine can prevent airsickness in passengers, they are not recommended while flying since they can cause drowsiness and other problems

Vertigo

A condition where you mistakenly think you’re accelerating in a particular direction

One form of spatial disorientationCan be experienced as a feeling of dizziness

and imbalance that can create or increase illusions

Spatial Disorientation

The lack of orientation with regard to the position, attitude, or movement of the airplane in space

Your orientation systems work very well for walking around; not so good for flying, particularly when flying in a cloud without benefit of your visual system

Without visual clues, your somatosensory and vestibular systems will lie to you every time

Without visual clues, you must disregard what your body tells you, and use aircraft instruments for orientation

Sensory Illusions

All these illusions require loss of visual clues. If you can see the horizon, you won’t experience them: The leans Coriolis illusion Graveyard spiral Somatogravic illusion Inversion illusion Elevator illusion

The Leans

Can result when a banked attitude, to the left for example, may be entered too slowly to set in motion the fluid in the “roll” semicircular tubes.

An abrupt correction of this attitude sets the fluid in motion, creating the illusion of a banked attitude to the right

The disoriented pilot may make the error of rolling the aircraft into the original left banked attitude, or if level flight is maintained, will feel compelled to lean in the perceived vertical plane until this illusion subsides

Coriolis Illusion

Occurs when a pilot has been in a turn long enough for the fluid in the ear canal to move at the same speed as the canal

A movement of the head in a different plane, such as looking at something in a different part of the flight deck, may set the fluid moving and create the illusion of turning or accelerating on an entirely different axis

The disoriented pilot may maneuver the aircraft into a dangerous attitude in an attempt to correct

Coriolis Illusion

It is important that pilots develop an instrument cross-check or scan that involves minimal head movement

Take care when retrieving charts and other objects in the flight deck—if something is dropped, retrieve it with minimal head movement and be alert for the coriolis illusion

Graveyard Spiral

A pilot in a prolonged coordinated, constant-rate turn, will have the illusion of not turning

During the recovery to level flight, the pilot will experience the sensation of turning in the opposite direction

The disoriented pilot may return the aircraft to its original turn

Graveyard Spiral

Because an aircraft tends to lose altitude in turns unless the pilot compensates for the loss in lift, the pilot may notice a loss of altitude

The absence of any sensation of turning creates the illusion of being in a level descent

The pilot may pull back on the controls in an attempt to climb or stop the descent

This action tightens the spiral and increases the loss of altitude

Graveyard Spiral

Somatogravic Illusion

A rapid acceleration, such as experienced during takeoff, stimulates the otolith organs in the same way as tilting the head backwards

This action creates the somatogravic illusion of being in a nose-up attitude, especially in situations without good visual references

The disoriented pilot may push the aircraft into a nose-low or dive attitude

A rapid deceleration by quick reduction of the throttle(s) can have the opposite effect, with the disoriented pilot pulling the aircraft into a nose-up or stall attitude

Inversion Illusion

An abrupt change from climb to straight-and-level flight can stimulate the otolith organs enough to create the illusion of tumbling backwards, or inversion illusion

The disoriented pilot may push the aircraft abruptly into a nose-low attitude, possibly intensifying this illusion

Elevator Illusion

An abrupt upward vertical acceleration, as can occur in an updraft, can stimulate the otolith organs to create the illusion of being in a climb

The disoriented pilot may push the aircraft into a nose-low attitude

An abrupt downward vertical acceleration, usually in a downdraft, has the opposite effect, with the disoriented pilot pulling the aircraft into a nose-up attitude

Let’s see your certificate

Title 14, Code of Federal Regs

Title 14, Aeronautics and SpaceCommonly referred to as Federal Aviation

Regulations, or FARs, which they used to be called

Divided into Parts, many of which are of interest to pilots Part 1, Definitions and Abbreviations Part 61, Certification: Pilots, Flight Instructors, and

Ground Instructors Part 91, General Operating and Flight Rules

NTSB 830

NSTB is National Transportation Safety Board

Now found in 49 CFR Part 830Notification and Reporting of Aircraft

Accidents or Incidents and Overdue Aircraft, and Preservation of Aircraft Wreckage, Mail, Cargo, and Records

Defines accidents and incidentsGives requirements regarding whom to

report to and deadlines for reporting accidents and incidents